The present invention relates to equipment for the production of screw-threaded drilled holes (tapped holes) of variable diameters in a single-pass operation with the use of an integrated cutting tool for similar types of threads which have a similar pitch [Example : M 14 and M 16 or M 18-20+M 22 (M =metric thread)]and with the use of a commercially-available hand-drilling machine having an electronically-controlled motor drive, or any other type of drive, the speed of rotation of which may be regulated in order to adapt it to the nature of the material being worked with. In addition, the invention also relates to a tool which is suitable for general use in CNC-controlled (Computer Numerical Control) milling machines and drilling machines from 21/2-D upward, more particularly in combination with a device which may be attached to a hand-drilling machine or the like for the production of tapped drilled holes in solid materials with the possibility of infinitely variable adjustment of the thread clearance. The objective of this method of working is to produce the core hole and the screw-thread in a single-pass operation.
Tapped drilled holes are produced in solid material either by preliminary drilling and subsequent tapping, or else by means of a so-called tapping drill in a single-pass operation. The first of these methods is time consuming and therefore expensive, but the other known method is only suitable for tapped drilled holes of limited diameter and its use is restricted to holes which are open at both ends. In addition to this, the known methods of working require the use of a tool of specific dimensions corresponding to the diameter of the particular tapped hole required. In many cases, especially for screwing into relatively soft materials, wood for example, it is additionally desirable for the diameter of the tapped hole to be made slightly smaller than the diameter of the screw-threaded bolt to be used, so that when the bolt is screwed in there will be a certain amount of compression of the material in the threaded region. In the methods formerly employed, expensive special tools were required which added greatly to the cost of the operation. For this reason there is a dearth of equipment with which, despite the integrated equipment and the use of an integrated tool, tapped holes of different diameters with different types of threads can be produced in solid materials without involving time-consuming and expensive operations.